Research: replace AnonType with Tuples?

[AlekseyMartynov]

var q = new Model1().Products.Select(p => new {
    Item1 = p.ProductID,
    Item2 = new {
        Item1 = p.ProductName
    }
});

can be built as

var p = Expression.Parameter(typeof(Product));

var t1 = typeof(Tuple<int, Tuple<string>>);
var t2 = typeof(Tuple<string>);

var q = new Model1().Products.Select(
    Expression.Lambda<Func<Product, Tuple<int, Tuple<string>>>>(
        Expression.New(
            t1.GetConstructor(new[] { typeof(int), t2 }),
            new Expression[] {
                Expression.Property(p, "ProductID"),

                Expression.New(
                    t2.GetConstructor(new[] { typeof(string) }),
                    new Expression[] {
                        Expression.Property(p, "ProductName")
                    },
                    t2.GetProperty("Item1")
                )

            },
            t1.GetProperty("Item1"),
            t1.GetProperty("Item2")
        ),
        p
    )
);

TODO check compatibility:

• EF (ok >= 4.3)
• EF Core (ok 1.0.6, 2.1.0)
• XPO (18.1.3 Select ok, GroupBy fails, fix requested)
• NHibernate (ok 5.1)

[AlekseyMartynov]

Code: https://github.com/DevExpress/DevExtreme.AspNet.Data/tree/experiment/tuples

Pros:

• No need for custom types (AnonType)
• Unlimited length

Cons:

• Incompatible with current XPO
• Access by index is not in .NET Standard, requires Reflection (Adding ITuple to .NET Standard dotnet/standard#628)